The problem of scanning barcodes can be applied to a large variety of application contexts, in the present application, without loss of generality, we concretely address a specific example in the engineering of a barcode reader in an electromechanical system for biological analyses. In particular, the barcode reading system has been implemented in the The Vitek ImmunoDiagnostic Assay System manufactured and distributed by bioMerieux also known as VIDAS® or VIDAS® 3 in its more recent version. It is a compact automated multiparametric immunoanalyzer that uses predispensed disposable reagent strips and specially coated Solid Phase Receptacles (SPR®). The VIDAS® 3 can pipette directly from the primary sample tube, mix, incubate, control and analyze samples.
The VIDAS® 3 has four independent sections, where each section can run up to 3 samples. Additional features allow the VIDAS® 3 to perform sample handling from primary tubes automatically. The operator introduces the centrifuged, uncapped tubes, SPR® and strips into the instrument. All remaining operations (barcode reading of the primary tubes and sample aspiration from primary tubes) are handled by the system automatically. VIDAS® 3 reagent strip processing, algorithms, analysis and kit components used (strips, SPR®, etc.) are all identical to the current VIDAS® and mini VIDAS®. Like the VIDAS® and mini VIDAS®, the VIDAS® 3 will offer routine batch or random access (mixed) testing for serology, immunochemistry, antigen detection and immunohemostasis. The immunological methods are indirect EIA, immunocapture, sandwich or competition, all involving a conjugate using the alkaline phosphatase. Like the VIDAS® and mini VIDAS®, the VIDAS® 3 uses instrument protocols as defined for each assay product. These protocols are automatically selected in the computer knowledge base through bar-coded information on the product packaging. The user confirms assay selection through user menus. Test results are transmitted to the computer to be analyzed and printed.
The system is able to concurrently run multiple analyses, which comprise sequences of actions performed on the sample by shared mechanical components; the maximum duration of each analysis is limited by biological constraints, but waiting times between subsequent actions are allowed to range in a non-deterministic interval.
Each type of biological analysis is comprised by a pretreatment phase and an analytic protocol. At the beginning of the analysis, a cone shaped test-tube uniquely identified by a barcode contains the sample, other tubes arranged as a strip of multiple containers, contain dilution and incubation fluids. During the pretreatment phase, an automatic pipettor repeatedly pours off the sample among the various tubes; each pipettor action lasts for a deterministic amount of time. Waiting times are allowed between successive actions, but they are constrained to range between minimum and maximum values determined by incubation/reaction periods and sample deterioration properties. After completion of the pretreatment phase, the analytic protocol follows a fixed sequence of steps during which the sample is combined with reagents and multiple measurements are taken by a read-head.
Also in this case, read-head actions are deterministic and interleaved with waiting times (see FIG. 1). For efficient exploitation of electromechanical components, multiple analyses, also of different types, are carried out concurrently. To this end, the system composes multiple sections, one for each analysis. Each section is in turn divided in slots, carrying different samples that can be subject to different pretreatments and can operate on samples of different subjects. However, since the read-head is designed to take measures on a whole section at once, all slots in the same section are constrained to run the same analytic protocol (see FIG. 2).
The pipettor and the read-head are shared among different slots and sections and cannot be used simultaneously by two different analyses.
In such biological analyses, it is of course essential that the right cone matches with the right strip. The insertion of the cones and the strips in the machine is normally done manually by an operator. The arrangement with multiple sections and slots makes even easier making a mistake in the position of the pair cone/strip. Several methods of emphasizing the matching between the two matching components have been put in place (e.g. same color on cone and strip), in order to facilitate the operation by the human operator. However, to make sure that the analyses are performed correctly, the machine should be better provided with an automatic recognition mechanism to avoid any human error. Barcode reading seems to be one of the possible solution, with a barcode (e.g. a 2D barcode) on the cone-shaped tube and a barcode on the strip: however the particular shape of the cone poses some problems in the automatic localization and reading of the barcode on the circular label on top of the cone (see FIG. 3). Known image recognition methods and software are quite expensive in terms of resource and time consumption. An additional difficulty of the present system is the possible inclination of barcode reader with respect to the circular label carrying the code, due to the relative positioning of the various components of the machine which does not allow a straight alignment between the reader and the target.
A simplified, faster and less hardware resource consuming solution would be therefore highly desirable.